Inserta el video en la posición original, eliminando kt_player y la imagen
< THISVID.COM_VIDEO DOWNLOADERについてのフィードバック
Thank you, any other recommendations please feel free to comment.
Welcome :) You can find my version based on your code here:
https://greasyfork.org/en/scripts/526331-thisvid-com-native-player-html5-and-download/code
Optimization: After appending the newVideoElement add line newVideoElement.play(); below so the video plays directly after first click (as it would with the original player) and no second click to play the video is needed.